Design and Simulation of Double Rotor Dual-Stage Hybrid Vertical Axis Wind Turbine for Power Generation

Abstract

The release of carbon emissions and other pollutants resulting from the combustion of fossil fuels constitutes a significant environmental challenge. Throughout the years, numerous initiatives have been undertaken to mitigate or diminish these emissions, notably through the adoption of renewable energy sources as viable alternatives. Wind energy is classified as a renewable energy source that is harnessed through wind turbines to transform wind energy into mechanical and electrical energy. Wind turbines exhibit a diverse array of types, designs, and dimensions. Nevertheless, such designs and their corresponding types encounter various challenges, which include, but are not limited to, inadequate starting capabilities, suboptimal efficiency, and a propensity for unidirectional wind acceptance (specifically about horizontal axis wind turbines). In response to these challenges, this paper delineates the design and simulation of a dual-rotor, two-stage hybrid vertical axis wind turbine (DRDSH VAWT) intended for small-scale power generation. The DRDSH turbine is comprised of a 3-blade modified Savonius Bach-type rotor in conjunction with a 3-blade two-stage Darrieus turbine. Computational fluid dynamics (CFD) simulation models are employed to analyze and evaluate the performance of the turbine. The findings of the study indicated that the power coefficient (CP) of the DRDSH VAWT experienced a 71.4% increase at a tip speed ratio (TSR) of 0.563 in comparison to a 3-bladed dual rotor conventional vertical axis wind turbine (DRC VAWT). Additionally, the moment coefficient (cm) of the DRDSH VAWT exhibited a 55.2% increase at a TSR of 0.560 relative to the DRC VAWT. The DRDSH VAWT also generated 35.8% more power than the DRC VAWT, demonstrating a direct correlation between wind speed and power output. Furthermore, this indicates that the CP of the DRDSH VAWT improved by 63.7% with increasing wind speed when compared to the DRC VAWT. CFD analysis revealed that the turbine is optimally suited for lower TSRs. During the initiation phase, a practical and efficient switching mechanism was integrated to facilitate the assistance of the Bach-type rotor to the DRDSH VAWT, thereby enhancing the efficiency of the turbine.